Several types of closures or fasteners are available for reclosing a previously opened flexible package. For example, it is common to use mechanical reclosable fasteners, such as slider zippers, clips, tabs, interlocking strips, and the like. Such mechanical closures can have colored and/or uncolored interlocking components that can both reclose a package and indicate to a user that the package has been reclosed. Such mechanical closures can be expensive, bulky, complex structures that require separate molding and fabrication steps prior to being joined to the flexible film used to form the package. In addition, while mechanical closures can be applied in form-fill-seal operations, the mechanical closures often require complex and expensive manufacturing steps to apply, interconnect, and align the mechanical fastening features of each structure. Therefore, mechanical reclosable fasteners often add undue complexity and cost to the manufacturing process of the flexible packages.
Adhesive-based reclosable fasteners provide one alternative to the mechanical fasteners. For example, thermoplastic elastomers, which are sometimes called thermoplastic rubber, have been used to form reclosable pressure sensitive adhesive type fasteners. Some types of thermoplastic elastomer copolymers (especially certain styrenic block polymers) demonstrate high cohesive properties, and at the same time have low tack levels or a reduced tendency to adhere to unlike materials (i.e., food materials such as cookies, crackers, shredded cheese and the like). Such adhesive-based reclosable fasteners typically include adhesive material, typically in the form of strips, formed opposite one another on interior surfaces of the side walls of the packages. One draw-back of the known adhesive-based reclosable fasteners is that they do not typically provide an indicator to tell the consumer whether the package has been properly or improperly closed or reclosed. While some adhesive-based reclosable fasteners include color-changing indicators, such color-changing indicators may be ineffective for some users because the color change is not readily apparent, and for other users because they happen to be color-blind. Further, production of such color-changing adhesive-based reclosable fasteners adds complexity and cost to the flexible packaging manufacture.